Mineral oil composition



Patented Apr. 23, 1940 UNIED STATES PATENT OFFICE MINERAL OIL COMPOSITION No Drawing. Application October 8,

Serial No. 234,046v

10 Claims.

This invention has to do in a general way with mineral oil compositions and is more particularly concerned with the production of mineral oil fractions of the viscous type, such as are used for lubricants, dielectrics, etc., which have-been improved by the incorporation therein of a minor proportion of an oil-miscible metalorganic compound capable of inhibiting the deleterious eliects of oxidation upon the oil.

It is well known that the ordinary lubricating oils, such as those used in internal combustion engines, for example, are susceptible to oxidation under normal conditions of use and, as the result of such oxidation, develop substantial quantities of carbonaceous material which accumulates as sludge or carbon deposits impairing the free flow of the oil. This carbonaceous material also accumulates about the piston rings, causing them to stick and filling the slots in the oil rings. Oxidation of the oil also develops substantial acidity in the oil which is corrosive to metals, particularly certain types of alloy bearing metals, and in the event the oil is used as a dielectric, the development of acidity obviously reduces its dielectric eiiiciency.

Numerous oxidation inhibitors have been proposed for use in mineral oils and the present invention is predicated upon the discovery of a novel class of compounds or compositions having this oxidation inhibiting action and has as its primary object the production of a mineral oil composition containing one or more of the oxidation inhibiting agents falling into this general class of compounds, to be hereinafter described.

As has been previously indicated, the materials contemplated herein as mineral oil-improving agents are metalorganic compounds. More specifically, these compounds or compositions may be classified as oil-miscible metal salts of keto acids.

The keto acids from which these metal salts are derived may be formed by the reaction of the anhydrides of aliphatic or aromatic acids with aliphatic, cycloaliphatic and aromatic compounds in the presence of a Friedel-Crafts catalyst. The

alkali metal saltsare formed by neutralizing the acid with a hydroxide or alcoholate of an alkali metal, and the polyvalent metal salts are obtained by double decomposition of the alkali metal salts with a salt of the desired metal.

In the event the keto acids are formed from the anhydrides of aromatic dibasic acids, the aryl nucleus of the anhydride may contain mineral oil-solubilizing substituents such as hydrogen,

halogen, alkyl, aralkyl, and alkoxy radicals or groups; and in case an aromatic hydrocarbon is used as the reactant with the anhydride, such aromatic compound may also have solubilizing substituents of the type illustrated by the examples given above.

Mineral oil-soluble salts of the type contemplated herein as oil-improving agents can. be formed, for example, from keto acids obtained by hydrolizing the products prepared (a) by the reaction of polybasic acid anhydrides with hydrocarbons from petroleum such as gasoline, kerosine, gas oil, petrolatum, and waxes; (b) by the reaction of anhydrides with cycloaliphatics such as cyclohexane, methyl cyclohexane, etc., and by the reaction of anhydrides with aromatic and mixed aromatic hydrocarbons containing halogen, hydrogen, hydroxy, alkyl, aralkyl, alkoxy, oi aroxy'substituents, such as toluene, chlorbenzene, amyl naphthalene, amyl phenyl ether, tetrahydronaphthalene, etc.

The keto acid salts of the type contemplated by this invention may be represented by the general formula:

in which R represents an aliphatic group, a cycloaliphatic group, an unsubstituted aromatic group, or an aromatic group having at least one substituent selected from the group consisting of hydrogen, hydroxy, halogen, alkyl, aralkyl, alkoxy, and aroxy radicals or groups; R represents an aliphatic group, an unsubstituted aromatic group, or an aromatic group which may have one or more substituents selected from the group consisting of hydrogen, hydroxy, halogen, alkyl, aralkyl, alkoxy, and aroxy radicals or groups; and M represents the hydrogen equivalent of a metal.

In the case of salts of polybasic metals, we may, by a modified procedure to be hereinafter described, form basic metal salts of the general type discussed above. Such basic salts may be represented by the general formula:

0 (.ranaojanomt wherein R and R havethe same significance indicated above; M represents a polyvalent metal having a valence V of two or more; n is a whole number equal to one or (v-n') and n is a whole number equal to one or (v-.-n).

The metal substituents in the carboxyl groups of the keto acid salts contemplated herein as oxidation inhibitors for mineral oils may be broadly classified as the metals belonging to the silver, copper, tin, aluminum, iron, alkali and alkaline earth analytical groups which include: silver, mercury, lead, and thallium; bismuth, copper, and cadmium; sodium, potassium, and lithium; arsenic, antimony, and tin iron, cobalt, nickel, and manganese; and barium, calcium. strontium, and magnesium, respectively. Other desirable metals include: titanium, cerium, tho

EXAWLE I.

Asorr. ALIPHA'I'IO Acme BY REACTION OF Anomarzo Hxnsocannous WITH ANHimarnEs or Amrna'no Dressrc Aco ns One mole of succinic anhydride and one mole oramyl naphthalene are dissolved in a chlorihated solvent such as tetrachlorethane, and two mols of anhydrous aluminum chloride, or other suitable Friedel-Crafts catalysts, is added to the solution with stirring at room temperature.

ter the aluminum chloride has been added, the mixture is heated to a temperature of about F. during a three-hour period to complete the reaction. The reaction mixture is then hydrolyzed and purified by washing with water containing suficient mineral acid to remove the aluminum, after which it is water-washed until neutral.

At this stage the keto acid can be used in the preparation of the metal salts without removal of the solvent.

Other keto aliphatic acids can be prepared by the foregoing procedure, using anhydrides oi other aliphatic dibasic acids such as maleic, adipic, sebacic, pimelic, and suberic acid; also another aromatic or substituted aromatic hydrocarbon may be used as the reactant with the an ydride.

EXAMPLE II Aron. Asona'rrc Acme BY REAUHON or Ahomrrc AND Mrxnu Anotrarro Hmsoosneous WITH AN- nrnsrnns or ABOMATIC DIBASIC Acme An illustrative reaction mixture for this synthesis is one mole of phthalic anhydrlde, one mole of amyl naphthalene, and two mols of aluminum chloride. The conversion to the keto acid is carried out according to the above-described synthesis of keto aliphatic acid. Orthophthalic'anhydride is preferred in the synthesis of keto benzoic acids, but the meta and para acid anhydrides are also applicable to the reaction and to the formation of mineral oil-soluble salts.

When unreacted dibasic acid remains after the formation of the keto acid, greater difllculty is encountered in its removal than in the case of the aliphatic dibasic acids. Unreacted phthalic acid can be removed by water-washing the solution of the keto acid. As a special procedure, the solvent can be removed and the product dissolved in water in the form of the sodium salt, after which the free acid can be precipitated by neutralizing the solution with a mineral acid. By repeating the solution and reprecipitation of the keto acid, complete removal of unreacted dibasic acid is insured. It is important to eflect complete removal of the unreacted acid because the reaction in which the salt is formed also converts unreacted dibasic acid to the corresponding salt which will form a cloud in mineral oil. The product of this procedure, using orthophthalic anhydride and amyl naphthalene is amyl mphthoyl-o-benzoic acid.

EXAIWPLEIII Ku'ro Acme Forum BY ran Rumor: or Aurna'rrc AND Cronosmmno Hxnnocsnaous WITH THE Axnxnamma or Dmasrc Acms An illustrative reaction mixture for this procedure is one mole of phthalic anhydride (or succinic anhydride) one mole of Stoddard solvent and two moles of aluminum chloride. The formation" of the keto acids from the aliphatic and cycloaliphatic hydrocarbons is carried out by the same procedure described under Example I above, but a higher reaction temperature (about 250 F.) is desirable to complete the reaction in the specifled period oi time.

When low boiling aliphatic and cycloaliphatic hydrocarbons are used, it is more suitable to use the above proportions of reactants and to prolong the time of reaction. Cyclohexane, for example, can. be condensed with phthallc anhydride by heating the reactants at 175 F. during a fivehour period.

EXAMPLE IV Sam-s or Ks'ro Acme A. Alkali Metal Salts B. Other: Neutral Metal Salts A keto acid of the type obtained by the pro cedure of Examples I, II, or m is dissolved in a suitable solvent such as a chlorinated solvent (tetrachlorethane) or a hydrocarbon solvent (Stoddard solvent, benzol, toluene, or the like). The acid solution thus formed is neutralized with an aqueous solution of sodium hydroxide (20% NaOH) using phenolphthalein as an indicator. To the neutralized solution containing the sodium salt of the keto acid is added one mole equivalent of an inorganic salt of the desired metal. The mixture is stirred for about half an hour'to complete the metathesis. The metal keto acid salt solution is then water-washed and the solvent distilled ofl to obtain the finished product which is a salt corresponding to general Formula I.

C. Basic Salts of Polyvalent Metals Salts of this type, satisfying general'Foi-mula II, are obtained by using two mole equivalents of alkali hydroxide to neutralize the keto acid in the procedure of 13 above and thereafter forming the salts of polyvalent metals by double decomposition with an aqueous solution of an inorganic salt of the desired metal in an amount equivalent to the hydroxide used. The basic cobaltous salt or amyl naphthoyl-o-benzoic acid can be prepared with reactants in the following proportions:

' Hols Amyl naphthoyl-o-benzoic acid- "1 sodium hydroxide 2 Cobaltous chloride 1 The acid is dissolved in benzol and neutralized with NaOH solution 20% NaOH) using phenolphthalein as an indicator and thereafter addin another mole equivalent of the hydroxide. .An aqueous solution of cobaltous chloride equivalent to the sodium hydroxide is then added and the reaction mixture stirred for about thirty minutes to complete the double decomposition. The finished product is obtained by further waterwashing of the benzol solution to effect complete removal of the reaction salts, followed by separation from the water and distillation of the benzol diluent.

The metal salts of keto acids of the type described above are eiiective oxidation inhibitors for viscous mineral oil fractions and are also capable of effecting a slight increase in the viscosity of such oil.-

To demonstrate the extent to which a mineral oil blend containing a keto acid salt of the type described above has been improved over the unblended oil, we have prepared a lubricant composition by blending one-fourth per cent of the cobaltous salt of amyl naphthoyl-o-benzoic acid with a mineral lubricating all stock of seconds Saybolt viscosity at 210 F., and we have made comparative tests with the oil blend and the oil alone. These tests were carried out in a single cylinder C. F. R. engine operated 'for twenty-eight hours at about 1200 R. P. M. with the engine-cooling medium held at a temperature of about 390 F. The oil'temperature remained in the neighborhood of F. during the test.

At the end of the test the piston was examined for stuck rings and ring slots filled with carbonaceous deposit. The acidity or neutralization number (N. N.) and the weight in grams ofcarbonaceous deposit (C. D.) in the used oil were also determined. The comparative results ob-- tained are listed in Table I below where oil A indicates the oil alone and oil 3 indicates the blend.

From the foregoing results it will be seen that metal salts of keto acids of the type contemplated herein, when blended with a viscous mineral oil fraction, retard to a substantial degree the deleterious efiects of oxidation. These keto acid salts may be blended with mineral oil fractions in various proportions depending on the oil fraction and the conditions under which it is to be used. In general a satisfactory product may be obtained with about one-fourth per cent of the improving agent, but amounts ranging from one-sixteenth per cent to two per cent may be used.

We claim:

1. a mineral oil composition of the type adapt ed for use as a lubricant or the like comprising a viscous mineral oil fraction and in admixture.

therewith a minor proportion, suflicient to inhibit oxidation of said oil, of an oil-miscible metal salt of a keto acid.

2. A mineral oil composition or the type adapted for use as a lubricant or the like comprising a viscous mineral oil traction and in admixture therewith a minor proportion, suilicient to inhibit oxidation of said oil, of an oil-miscible metal salt of a keto acid formed by hydrolyzing the Friedel-Crafts condensation product of the anhydride of a polycarboxylic acid and a hydrocarbon material.

3. A mineral oil composition of the type adapted for use as a lubricant or the likecomprising a viscous mineral ofl fraction and in admixture therewith a minor proportion, sufiicient to inhibit oxidation of said oil, of an oil-miscible metal salt of a keto acid formed by hydrolyzing the Friedel-Crafts condensation product of the anhydride of a polycarboxylic acid and a hydrocarbon material selected from the group consisting of aliphatic hydrocarbons, cycloaliphatic hydrocarbons, unsubstituted aromatic hydrocarbons, and aromatic hydrocarbons having substituents selected from the group consisting of hydrogen, hydroxy, halogen, alkyl, aralkyl, and aroxy groups.

4. A mineral oil composition of the type adapted for use as a lubricant or the like comprising a viscous mineral oil fraction and in admixture therewith a minor proportion, suflicient to inhibit oxidation of said oil, of an oil-miscible metal salt oi a keto acid formed by hydrolyzing the Friedel-Crafts condensation product of the anhydride of an acid selected from the group consisting of aliphatic and aromatic polybasic acids and a compound selected from the group consisting of aliphatic hydrocarbons, cycloaliphatic hydrocarbons, unsubstituted aromatic hydrocarbons and aromatic hydrocarbons having substituents selected from the group consisting of hydrogen. hydroxy, halogen, 'alkyl, aralkyl, alkoxy, and aroxy groups.

5. A mineral oil composition of the type adapted for use as a lubricant or the like comprising a viscous mineral oil fraction and in admixture therewith a minor proportion, sumcient to inhibit oxidation of said oil, of an oil-miscible metal salt of a keto acid formed by hydrolyzing the Friedel-Craits condensation product of the anhydride of a dibasic aromatic acid and an aromatic hydrocarbon.

6. A mineral oil composition of the type adapted for use as a lubricant or the like comprising a viscous mineral oil fraction and in admixture therewith a minor proportion, sufiicient to inhibit oxidation of said oil, of an oil-miscible metal salt of a keto acid formed by hydrolyzing the Friedel-Crafts condensation product of the anhydride of a dibasic aliphatic acid and an aliphatic hydrocarbon.

'7. A mineral oil composition of the type adapted for use as a lubricant or the like comprising a viscous mineral oil fraction and in admixture therewith a minor proportion, sufllcient to inhibit oxidation of said oil, of an oil-miscible metal salt of a keto acid formed by hydrolyzing the Friedel-Crafts condensation product of the an hydride of a dibasic aromatic acid and a cycloal'iphatic hydrocarbon.

8. A lubricating oil composition comprising a viscous mineral oil fraction and in admixture therewith a minor proportion, sufiicient to inhibit oxidation of said oil, of the cobaltous salt oi? amyl naphthoyl-o-benzoic acid.

9. A mineral oil composition of the type adapted for use as a lubricant or the like comprising a viscous mineral oil fraction and in admixture therewith a minor proportion of a metal salt of a keto acid having the general formula:

in which R represents an aliphatic, cycloaliphatic, or aromatic hydrocarbon group or an aromatic hydrocarbon group having at least one substituent selected from the group consisting of hydrogen, halogen, hydroxy, alkyl, aralkyl, alkoxy, and aroxy groups; R represents an aliphatic hydrocarbon group, an aromatic hydrocarbon group, or an aromatic hydrocarbon group having at least one substituent selected from the group consisting of hydrogen, hydroxy, halogen, alkyl, aralkyl, alkoxy and aroxy groups; and M represents the hydrogen equivalent of a metal.

amuse 10. A mineral oil composition 01' the type adapted for use as lubricants, dielectrics, and the like comprising a viscous mineral oil fraction and in admixture therewith a minor proportion of a metal salt of a keto acid having the eneral formula:

o ((R',ii-n-('i-0).M-(0H).' in which R represents an aliphatic, cycloaliphatic or aromatic hydrocarbon group of an aromatic hydrocarbon group having at least one substituent selected from the group consisting of hydrogen, hydroxy, halogen, alkyl, aralkyl, alkoxy, and aroxy groups; R represents an aliphatic hydrocarbon group, an aromatic hydrocarbon group, or an aromatic hydrocarbon group having at least one substituent selected from the group consisting of hydrogen, hydroxy, halogen, alkyl, aralkyl, alkoxy, and aroxy groups; M represents a polyvalent metal having a valence v of two or more; n and n are whole numbers less than 12, n being equal to (D-71) and n being equal to (vn) ORLAND M. REIFF. ELWOOD M. JOHNSON.

Patent No. 2,197,836.

It is hereby certified ORLAND M. REIFF, I ET AL. that errors appear in the printed specification of the above April 23, 1940.

numbered Patent q g correctlon as follows-v P 4 claim 10, strike out the formula and insert instead the iollov i igg i column hue line 11, same claim, for of read or; and that the said Letters Patent should be read w1th these corrections therein in the Patent Office.

that the same may conform to the record of the case Signed and sealed this 19th day of November, A. D. 1940.

[snarl] HENRY-VAN ARSDALE,

Acting Commissioner of Patents.

Certificate of Correction Patent No. 2,197,836. April 23, 194:0.

. ORLAND M. REIFF, ET AL.

It is hereby certified that errors appear in the printed specification of the above numbered patent re uiring correction as follows:- Page 4, second column, line 7, claim 10, strike out t e formula and insert instead the followingline 11, same claim, for of read or; and that the said Letters Patent should be read with these corrections therein that the same may conform to the record of the case in the Patent Ofiice.

Signed and sealed this 19th day of November, A. D. 1940.

HENRY-VAN ARSDALE,

"Acting Commissioner of Patents. 

